Ao Zhenyuan had originally wanted to use the countless fierce ghosts in the ghost tribe army to exhaust Chu Fengmian's Spiritual Power.
Although these fierce ghosts were not very strong, they were extremely annoying and numerous, and even masses of ants can bite an elephant to death.
Even if a sacred being fell into their midst, it would take a considerable amount of effort to exterminate this army of fierce ghosts.
Ao Zhenyuan had no idea how many sacred beings he had killed using this tactic.
These common fierce ghosts could be easily obtained in great numbers by destroying a single sect, so naturally, he didn't care about using them up.
But what he could never have imagined was that Chu Fengmian actually possessed a way to neutralize this ghostly energy, which was extremely problematic even for sacred beings to tackle, requiring a great deal of effort to cleanse once contaminated.